1) Field of the Invention
The present invention relates to stents, in particular, to a stent removal and repositioning device that promotes removal or repositioning of a stent within a lumen.
2) Description of Related Art
Stents are devices that are inserted into body lumens such as vessels or passages to keep the lumen open and prevent closure due to a stricture, external compression, or internal obstruction. In particular, stents are commonly used to keep blood vessels open in the coronary arteries and they are frequently inserted into the ureters to maintain drainage from the kidneys, the bile duct for pancreatic cancer or cholangiocarcinoma, or the airways and esophagus for strictures or cancer. Vascular as well as nonvascular stenting has evolved significantly; unfortunately there remain significant limitations with respect to the technology for positioning and removing stents following implantation into various portions of a patient's anatomy.
In various areas of application, e.g., bronchus, biliary, trachea, or esophagus, the stents must be removable from the body or repositionable as a function of the course of the disease or treatment. This can be problematic since newly formed tissue can grow on the support frame of the stent and even grow through it, which can result in complications when removing a stent. In this regard, stents have been developed that include a support frame surrounded on the outside by a thread or wire. The support frame can be radially constricted by pulling on the thread ends that are each provided with a loop or the like, creating a “purse-string” effect, which makes it possible for the frame to be removed or repositioned. However, when the wire or thread is guided or braided in multiple windings around the support frame, a high degree of friction results between the two stent components, which has a disadvantageous effect on the explantation process. In addition, stents having eyelets for looping the thread therethrough may have sharp edges that cause the thread to tear or break during the removal process.
Alternatively, physicians have grasped the thread ends with forceps or a similar instrument to reposition or remove the stent from within the lumen. However, this can be complex at times when the tissue has grown over the suture thread. Also, the suture may not be strong enough to remove the stent. Grasping may lead to damage to the stent itself, as the forceps may have difficulty accessing or adequately gripping the thread to remove or reposition the stent. Physicians may also use grasping forceps to grab the struts of the stent at a proximal end and remove the stent from the deployment site, but this also risks damage to the lumen or the stent, as the proximal end of the stent may be difficult to access.
Thus, there is a need in the industry for a stent that reduces the risk of damage to the stent, thread or suture, and/or the surrounding tissue during removal or repositioning of the stent. In addition, there is a need for a stent that provides for greater accessibility, as well as promotes effective repositioning and/or removal of the stent from a lumen.